Build a Halbach Array

And a one-sided refrigerator Magnet!

The late Klaus Halbach of Lawrence Livermore National Laboratories discovered
an interesting permanent magnet configuration that concentrates magnetic flux on one side of the array
and cancels it on the other. He originally designed it for focusing the beams of particle accelerators. LLNL scientists Post and Ryutov developed the idea into a model Maglev
train, the only one so far that uses permanent magnets--it floats over a series of short-circuited coils
at only 5 mph or so (the 'Inductrack' system). Maglev trains, motors and generators using circular Halbach arrays have already been patented--the
advantages include minimized drag from eddy current effects (drag decreases as speed increases), reduced power consumption (no giant electromagnets needed), reduced exposure of train passengers to high magnetic fields, and other things that we haven't even begin to explore
yet.

Our only result from experimentation so far has been a one-sided refrigerator magnet.
Though it seems trivial at first, this magnet array seems frighteningly close to a magnetic monopole...it was enough
to freak out the entire Wondermagnet.com staff!

One side of it sticks to the fridge....but the other
does not.

To build our strange, one-sided refrigerator magnet, we simply routed out a slot in a piece of wood
to accept 5 of our Item #12, a 7/16 inch
Neodymium-Iron-Boron cube magnet. The magnets are difficult to place in the correct pole configuration--they
want to violently rotate into a N-S arrangement! First, mark the polarity of each magnet of the array
by testing it against another magnet. Observe the first diagram above for the proper polarity configuration.
It does not matter which pole is North and which is South, only that the poles you mark are the
same, and that they match the diagram above.

Using a C-clamp to hold a magnet down into the
slot, and another C-clamp to push each magnet toward the next, each magnet can be affixed into the slot
in the proper polarity configuration using
cyanoacrylate glue and accelerator, also available from us. Place one magnet at a time, and glue into the slot. If you
try to clamp and glue all of them down at once, they will rotate out of the proper alignment
and your experiment will fail!

In the photos below, the side that says 'augments' will stick to the fridge...but the side that says
'cancels' will not!

Magnetic Viewing Film Image of the Augmented Side

Magnetic Viewing Film Image of the Cancelled Side

Halbach arrays can also be constructed in a circular arrangement. This lends itself to applications with
motors and generators, and such designs have already been patented. The opportunities for the home remote power
enthusiast are limitless! We have not even begun our work in this direction...but we sure hope
others are interested too. Check out our other Halbach Array links for more
research material.